KR890003198B1 - Method of producing of magnetic recording carriage - Google Patents

Abstract

The magnetic recording medium is mfd. by forming a magnetic recording layer with a magnetic compsn. of magnetic powder and a binder resin. The prodn. process includes mechanically pulverizing and mixing the magnetic powder and the solid binder resin at room temp.. The magnetic powder is a hexagonal ferrite contg. a substituting element.

Description

Method of manufacturing magnetic recording medium

The present invention relates to a method of manufacturing a magnetic recording medium, and in particular to a method of manufacturing a magnetic recording medium which is improved in the preparation process of a magnetic composition for a magnetic recording layer.

Conventionally, a magnetic recording medium is prepared by mixing a γ-ferrite powder coated with Co on a needle-like γ-ferrite powder, a solvent, and a binder resin to prepare a magnetic paint, and for example, on a surface of a substrate such as a polyester film. It is prepared by coating and drying.

In recent years, high density recording has been demanded in the above-described magnetic recording medium, and as a method for realizing this, small particle hardening of the γ-ferrite powder, use of these reducing powders (metal powder), and the like have been considered. It is no exaggeration to say that the technical point of producing such a high density magnetic recording medium depends on whether or not these ultra fine powders are dispersed in a binder resin. For this reason, much effort is required for dispersion, and various methods have been examined to improve the dispersibility such as surface modification of magnetic components, development of various dispersers, processes, adoption of new dispersants and binder resins, and the like. Among them, the so-called wet dispersion method in which the magnetic powder is dispersed in a water or oil-based solvent with a disperser, a twisting machine, a bowl mill, a sand grinder, a paint shaker, and a disperser in addition to a dispersant or a binder resin is employed. . This is because needle-like γ-ferrite powder or metal powder, which is used for most applications except magnetic cards, is soft and brittle against mechanical stress, and metal powder is particularly easy to oxidize, In the dry state, there is a risk of igniting or exploding. As described above, since the magnetic paint is prepared by a complicated or complicated dispersing means, the problem of low productivity of the magnetic cross media always follows.

The present invention makes it possible to prepare a magnetic composition comprising a magnetic component and a binder resin by a simple operation, and to produce a magnetic recording medium in a mass production manner by using the magnetic composition as a starting material for forming a magnetic recording layer. I would like to provide a way to do it. The present inventors pay attention to the fact that the six-orbital ferrite powder containing the magnetic component, in particular, substituted elements, is stable against mechanical stress, and the six-orbital ferrite powder is added to the solid binder resin directly at room temperature without using a solvent, and then pulverized mechanically. The present invention has been found to prepare a magnetic recording medium of the purpose described by preparing a magnetic composition which is uniformly covered with a binder resin of 6-crystal ferrite powder and mixed with high efficiency by mixing.

That is, according to the present invention, when the magnetic recording layer is formed by forming a magnetic recording layer using a magnetic composition containing a magnetic component and a binder resin as a main component, the magnetic composition is mechanically pulverized with a solid binder resin at room temperature. And a method including a step of mixing.

As the magnetic component, a hexagonal ferride powder containing a substituted element is suitable. Such a six-crystal ferrite powder is a six-crystal ferrite represented by ordinary stone Mo'n (Fe ₂ O ₃ ), M is any one of Ba, St, Pb, and Ca, n is 5 to 6, and a part of Fe is It may be substituted by transition metals such as Ti, Co, Zn, In, Mn, Cu, Ge, and Nb. Such fine particles of hexagonal ferrite are regular hexagonal single crystals whose particle diameter is usually expressed by the length of the diagonal of the regular hexagonal plate, and the thickness of the plate is about 112 to 1/10 of the length of the diagonal, and the magnetization is easy to use. The axis is in a direction perpendicular to the plane. Moreover, it is preferable to use the magnetic component which is hard to sinter and dry aggregation from a viewpoint of achieving high dispersion.

Although the sintering of the magnetic component is largely dependent on the production method, there is almost no sintering of the magnetic component produced by the glass crystallization method, and thus it is bonded to the method used in the present invention. On the other hand, in order to worsen the cohesion force of a magnetic component, it is achieved by performing the elevation treatment of a magnetic component beforehand. Examples of the surface treatment methods include, but are not limited to, various binders such as Ti-bonds, Si-bonds, Al-bonds, and Zn-bonders, treatment plasma treatments with various clade agents, and surfactant deposition treatments. . In the case where the magnetic component subjected to such treatment or the like is used as a magnetic recording medium for magnetic tapes or discs, in order to firmly bind with the binder resin, it is excellent in mechanical properties such as wear resistance and can maintain stable dispersibility even in a coating state. It has many advantages in practical use in displaying excellent electron change characteristics.

The binder resin is limited to the solid one at the time of dispersion. Therefore, in general, solid resins are preferable at room temperature, but in particular, when dispersing while cooling, there is no problem as long as they are solid at the time of dispersion even if they are liquid at room temperature. The shape of the binder resin may be in the form of a bulk or a petet, but is preferably used in powder form from the viewpoint of improving the dispersion efficiency. As such binder resins, for example, vinyl chloride copolymers represented by vinyl chloride, vinyl acetate, vinyl, alcohol copolymer, vinyl chloride, vinyl acetate, maleic anhydride polymer, vinyl chloride acrylic copolymer, vinyl chloride acrylic maleic anhydride copolymer, and the like. Or vinylidene chloride, polyvinyl alcohol, polyvinyl thermal, polyvinyl butyral, polyvinyl acetal, polyester, polyurethane, polyacrylade, polycarbonate, polyethyl, polyacrylic acid, polyvinyl pyridene, poly Thermoplastic or epoxy resins such as P-vinylphenol, polyacrylonitrile, polyamide resin, cellulose resin, and phenoxy resin, unsaturated polyester, phenol resin, melamine resin, urea resin, furan resin, and xylene resin And thermosetting resins such as ketong resins. These binder resins are used by one type or a mixture of 2 or more types. It is preferable to mix | blend 5-200 weight part of binder resin with respect to 100 weight part of magnetic components in the compounding ratio of the said magnetic component and binder resin. This reason is that when the blending amount of the binder resin is less than 5 parts by weight, the dispersibility of the magnetic component is lowered, and the stability at the time of solvent dilution or magnetic field orientation is also lowered.

On the other hand, if it exceeds 200 parts by weight of the blending amount of the binder resin, the magnetic properties required as the magnetic recording medium cannot be obtained.

The pulverization and mixing of the magnetic powder and the binder resin, that is, the dry dispersion, uses an apparatus such as a mixer, a Henschel mixer, an atomizer, an atomizer, or the like. In the case of dry dispersion of the magnetic component and the binder resin using these dispersion mixers, the dispersion conditions are set in consideration of the melting point of the binder resin, but the dispersion time is usually 1 to 60 minutes. It is preferable to carry out in the range of 150.

Moreover, in dry dispersion, various additives may be added beforehand, and it is also possible to disperse | distribute with a low component and a mind resin. Examples of the additive include antistatic agents such as carbon, graphite (graphite), various polishing agents substituted with chromium oxide and alumina, inorganic powders such as calcium carbonate and magnesium oxide silica, fatty acids, fatty acid esters, fatty acid amides, silicone oils, Lubricants, surfactants, stabilizers, mold release agents, pigment dyes, anti-aging agents, surface treatment agents, plasticizers and the like such as prolocabon are usually added within 50 parts by weight with respect to 100 parts by weight of the binder resin. In addition, additives other than the above may be used as long as 0.01 to 10 parts by weight.

According to the present invention, however, by mechanically pulverizing and mixing the magnetic component and the binder resin, it is possible to obtain a magnetic composition in which the magnetic component is uniformly coated with the resin by frictional heat or the like in a simple or short time treatment. The magnetic composition obtained in this way can be molded as is and used as a plastic magnet or hardist. In addition, when applied to magnetic recording media such as a magnetic tape or a floppy disk, the magnetic composition is let down with a solvent or resin, a magnetic paint is prepared at a desired concentration and viscosity, and the magnetic paint is polyester. What is necessary is just to apply | coat on nonmagnetic support bodies, such as a film, and to perform processes, such as drying. In such a let down, even if it uses a disperser, such as a colloid mill, a paint shaker, a homogenizer, and a dissolver, it does not interfere at all.

Hereinafter, embodiments of the present invention will be described in detail.

Example 1

First, a substituted barium ferrite powder (MS: 59emu / g, Hc: 780Oe) 2Kg of the chemical formula Ba'6 [(FeO.86 Co0.07 Ti0.07) ₂ O ₃ ] was charged with 100 g of conductive carbon and 100 g of alumina. Then, 200 g of vinyl chloride and vinyl acetate copolymer (trade name: VAGH, manufactured by UCC) were weighed, respectively, and these were put in a hexyl mixer and subjected to dry dispersion for 20 minutes while cooling to prepare a magnetic composition. The obtained magnetic composition was observed (800 times) with a scanning electron microscope, whereby the resin, barium ferrite powder, carbon and alumina were mixed and dispersed uniformly.

Subsequently, 2 Kg of a mixed solvent of methyl ethyl ketene / toluene (mixing ratio 1: 1) and polyurethane resin (trade name: N-2301 manufactured by Nippon Polyurethane Co., Ltd. product name: N-2301) were added to the magnetic composition, followed by sand Dispersion was performed for 2 hours using a grind mill. Subsequently, filtration was performed, and 30 weight% of polyisocyanate hardeners (trade name: Colonate L manufactured by Japan Polyurethane Co., Ltd.) were added to the resin to prepare a magnetic coating. Subsequently, the magnetic coating was applied onto a polyester film using a doctor blade to form a magnetic coating having a thickness of 3 µm. The coating was then passed through a supercalendar device, and the surface roughness of the magnetic recording layer was 0.04 µm or less. A magnetic recording medium was prepared.

The obtained magnetic recording medium was satisfactory at 161 ° in glossiness (60 ° -60 °).

Example 2

Hc : 780 Oe)100중량부에 대해 염화비닐 초산비닐공중합체(UCC 사제 상품명 : VMCH)10중량부를 가하고 믹서로 3분간 분산을 행하여서 자성조성물을 만들었다.First, the same barium ferrite powder as in Example 1 (MS: 59 emu / g)

10 parts by weight of vinyl chloride acetate copolymer (trade name: VMCH manufactured by UCC) was added to 100 parts by weight of Hc: 780 Oe), and the mixture was dispersed for 3 minutes to prepare a magnetic composition.

Then, 110.0 parts by weight of the magnetic composition, 1.5 parts by weight of olenic acid, 3.0 parts by weight of an oxide scrub, 2.0 parts by weight of palmitic acid, and 60.0 parts by weight of polymuretane resin (trade name: N-2301 manufactured by Nippon Polyurethane). , 70.0 parts by weight of methyl ethyl ketene and 60.0 parts by weight of toluene were dispersed in a paint conditioner for 2 hours. Subsequently, this dispersion was filtered, and 20% by weight of a polyisocyanate curing agent (trade name: Colonate L manufactured by Nippon Polyurethane Co., Ltd.) was added to the resin to prepare a low paint. Subsequently, the magnetic paint was applied onto the polyester film as an applicator, and the magnetic coating film was about 3.5 μm, then passed through a supercalendar device to polish the surface, and the half-width was further cut to cut the magnetic paint. Was prepared.

When the electron conversion characteristic (3.75 m / sec 4 MHz carrier) of the obtained magnetic tape was measured, it was an output: 210 microV and S / N ratio: 34.6 dB.

Comparative Example 1

A magnetic paint having the same composition as in Example 2 was prepared by wet dispersion treatment, and a magnetic tape was prepared in the same manner as in Example 2 using this magnetic paint.

The obtained magnetic tape was examined for characteristics of electron conversion by the same measurement method as in Example 2, and the output was 175 µV and the S / N ratio was 33.4 dB.

[Examples 3 to 6]

First, a mixture of 100 parts of barium ferrite powder and 10 parts by weight of vinyl chloride and a vinyl acetate copolymer (trade name: VAGH manufactured by UCC) as in Example 2 (Example 3), a Ti binder (trade name: 138S manufactured by U.S.A.G. A mixture of 101 parts by weight of copper barium ferrite powder coated with 1% and 10 parts by weight of a pupil polymer (Example 4), and 101 parts by weight of copper barium ferrite powder coated with 1% with a Ti binder (trade name: TTS manufactured by Ajino Modo Co., Ltd.) A mixture of 10 parts by weight of a polymer (Example 5) and 10 parts by weight of a copper barium ferrite bone and 10 parts by weight of a copolymer (Example 6) coated with 1% of a silane binder (trade name: A-187 manufactured by UCC) was respectively performed. Four kinds of magnetic compositions were prepared by performing the same dry dispersion treatment as in (2). Subsequently, the magnetic coating was prepared by dispersing the magnetic composition with an additive and a solvent as shown in the following table for 2 hours with a paint conditioner to prepare a magnetic coating.

Subsequently, a magnetic tape was produced in the same manner as in Example 2 using these magnetic paints.

Comparative Example 2-5

The same barium ferrite powder as in Example 3-6 was wet-dispersed together with the additives and solvents of the vinyl chloride acetate copolymer copper table to prepare magnetic tape by the same method as in Example 2 using four magnetic paints. It was. However, electron conversion characteristics of the magnetic tapes of Examples 3 to 6 and Comparative Examples 2 to 5 were evaluated. The result was recorded in the same table.

As is apparent from the above table, it can be seen that the magnetic tape of this Example 3-6 has superior output S / N ratio compared to the magnetic tape of Comparative Example 2-5. The magnetic tape of Example 4-6 using the barium ferrite powder treated with the binder showed that the barium ferrite powder, which was not treated with the binder, had excellent flight output and S / N ratio. . In particular, when the barium ferrite powder treated with the Ti-binder is used, a magnetic tape having excellent output and S / N ratio can be obtained.

As described above, according to the present invention, the dry method can prepare a magnetic composition in which the magnetic component and the binder resin are uniformly dispersed by simple operation, and use this as a starting material for forming the magnetic recording layer. It is possible to provide a method for mass-producing a magnetic recording medium having excellent N ratio.

Claims (2)

In preparing a magnetic recording medium by forming a magnetic recording layer using a magnetic composition mainly composed of a magnetic component and a binder resin, the process of mechanically grinding and mixing the magnetic composition with a solid binder resin at room temperature A method for producing a magnetic recording medium, characterized by comprising means for containing. The method of manufacturing a magnetic recording medium according to claim 1, wherein the magnetic component is a hexagonal ferrite powder containing a substituted element.